While Sigmund Freud might explain an individual's depression by focusing on the person's unconscious thoughts,a physiological psychologist might focus instead on a chemical imbalance in the brain.Which of your textbook's unifying themes is illustrated by this example

A)  Heredity and environment jointly influence behaviour. 
B)  Psychology evolves in a sociohistorical context. 
C)  Psychology is empirical. 
D)  Psychology is theoretically diverse.